A student has admitted building a bomb and leaving it on a Tube train but said it was for a prank, a court heard.
Damon Smith denies making or possessing an explosive substance with intent to endanger life but at the Old Bailey he admitted perpetrating a bomb hoax.
The prosecution said Mr Smith intended the Improvised Explosive Device (IED) to explode and endanger the lives of people on the Jubilee Line train.
Prosecutors said the IED contained ball bearings to act as shrapnel.
Jonathan Rees QC, for the prosecution, said this was to "increase the destructive effect of the device".
At the start of the trial, Mr Rees said the defendant told police he had built a device which when activated was intended only to produce smoke.
However, the defendant added the ball bearings because he wanted to make it look like a real bomb so the train would be stopped and it would be reported on the news, Mr Rees added.
The court heard the device was found by two passengers when Mr Smith got off the train at London Bridge station last October.
They handed it to a driver, Adrian Clarke, who initially thought it was for lost property but then, as he drove to North Greenwich, realised it contained two wires coming out of the back of a clock, the court heard.
The court heard the student had moved to Rotherhithe in south-east London with his mother from Newton Abbot, Devon, when he started a computer forensics degree at London Metropolitan University.
The defendant has Asperger's syndrome, or Autism Spectrum Disorder as it was known, and has a keen interest in guns and other weapons that may have been a function of the condition, the court heard.
The prosecution said officers had found:
- A blank self-loading pistol purchased in September 2016
- A carbon-dioxide powered revolver designed to fire ball-bearings, a knife in a sheath and a knuckleduster
- An examination of an iPad contained an image of the defendant standing in front of a TV screen showing a photograph of Abdelhamid Abaaoud, alleged to have masterminded the attacks in Paris in November 2015
- This also contained images of him posing with guns and a shopping list for "pressure cooker bomb materials"
- Shredded paper which when reconstructed was identified as being an article from an al-Qaeda online publication called Inspire first which gave details on how to build a pipe bomb
The court heard Mr Smith told police he had been brought up a Christian but was interested in Islam which he thought was "more true".
He did not really practise Islam, although he read the Quran and sometimes prayed in the morning when it was convenient but did not hold extreme views, the court heard.
Mr Rees said that on the day of the incident the defendant had started a timing mechanism on the device while he was at Southwark station, changing trains.
Meanwhile, Mr Smith went to his university campus at Holloway and searched for news articles on the incident when he got home later, the court heard.
The trial continues.